 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.internal.expressions;

 import java.util.ArrayList ;
 import java.util.Iterator ;
 import java.util.List ;

 import org.eclipse.core.runtime.CoreException;

 import org.eclipse.core.expressions.EvaluationResult;
 import org.eclipse.core.expressions.Expression;
 import org.eclipse.core.expressions.ExpressionInfo;
 import org.eclipse.core.expressions.IEvaluationContext;

 public abstract class CompositeExpression extends Expression {

     private static final Expression[] EMPTY_ARRAY = new Expression[0];

     /**
      * The seed for the hash code for all composite expressions.
      */
     private static final int HASH_INITIAL= CompositeExpression.class.getName().hashCode();
     
     protected List fExpressions;
     
     public void add(Expression expression) {
         if (fExpressions == null)
             fExpressions= new ArrayList (2);
         fExpressions.add(expression);
     }
     
     public Expression[] getChildren() {
         if (fExpressions == null)
             return EMPTY_ARRAY;
         return (Expression[])fExpressions.toArray(new Expression[fExpressions.size()]);
     }
     
     protected EvaluationResult evaluateAnd(IEvaluationContext scope) throws CoreException {
         if (fExpressions == null)
             return EvaluationResult.TRUE;
         EvaluationResult result= EvaluationResult.TRUE;
         for (Iterator iter= fExpressions.iterator(); iter.hasNext();) {
             Expression expression= (Expression)iter.next();
             result= result.and(expression.evaluate(scope));
             // keep iterating even if we have a not loaded found. It can be
 // that we find a false which will result in a better result.
 if (result == EvaluationResult.FALSE)
                 return result;
         }
         return result;
     }
     
     protected EvaluationResult evaluateOr(IEvaluationContext scope) throws CoreException {
         if (fExpressions == null)
             return EvaluationResult.TRUE;
         EvaluationResult result= EvaluationResult.FALSE;
         for (Iterator iter= fExpressions.iterator(); iter.hasNext();) {
             Expression expression= (Expression)iter.next();
             result= result.or(expression.evaluate(scope));
             if (result == EvaluationResult.TRUE)
                 return result;
         }
         return result;
     }
     
     public void collectExpressionInfo(ExpressionInfo info) {
         if (fExpressions == null)
             return;
         for (Iterator iter= fExpressions.iterator(); iter.hasNext();) {
             Expression expression= (Expression)iter.next();
             expression.collectExpressionInfo(info);
         }
     }

     protected int computeHashCode() {
         return HASH_INITIAL * HASH_FACTOR + hashCode(fExpressions);
     }
 }

